And that is very unusual actually. AMD is to release the B550 chipset soon, and motherboards normally would just get one M.2. slot at four PCIe gen 4.0 lanes. The chipset otherwise is Gen 3.0. So Gigabyte is being clever as frack and came up with a solution to bypass that limitation. 

Next to the single x4 lanes for one M.2. SSD, the Gigabyte B550 Aorus Master will split up the x16 PCIe Gen 4.0 graphics slot into a single 8x connection, that frees 2x four lanes. So any graphics card would run 8 lanes of PCIe Gen 4.0 and then all of a sudden you can use three m.2. SSDs at Gen 4.0. The B550 AORUS MASTER is a beefy one, it gets a 16-phase power supply, VRM cooling module, Realtek 2.5GbE network and Intel Wi-Fi 6 wireless.

The motherboard has reinforced RAM slots and the top PCIe slot is reinforced as well. It has 8+4 pins for the CPU which might indicate that this motherboard is designed with overclocking in mind. A release is expected in June, we'll see but this is a clever trick as x8 Gen 4.0 is the same bandwidth as x16 gen 3.0, e.g. any graphics card will run plenty fast on that slot.